S&P announces some changes to its index lineup today: Regeneron Pharmaceuticals (REGN) will join the S&P 500, replacing MetroPCS (PCS) which is being acquired by T-Mobile USA. S&P SmallCap 600 constituent Eagle Materials (EXP) will replace REGN in the S&P MidCap 400, and Francesca's Holdings (FRAN) will replace Eagle Materials in the S&P SmallCap 600 after the close of trading on Tuesday, April 30.